Ruby

Rubies are one of the "precious" gemstones and have been cherrished for centuries.  A member of the Corundum species, rubies are the birthstone for July.  Found in various shades of red, their name is derived from the Latin term for that color.  Chromium is the source for the ruby color with iron contributing to those with more brownish tones. 

Besides the diamond, ruby is the hardest mineral, although this will vary in different directions within the gemstone. Heat treatment is often used to improve coloring. It is common to find inclusions within rubies. Coloring has a lot to do with the value of rubies, but some of the finest rubies are not as opaque as the most commonly occurring rubies. 

STATS:
Color: Varying red
Mohs' Hardness Scale: 9
Density: 3.97 to 4.05
Transparency: Transparent to opaque

Natural Rubies

Natural Rubies in findings

Lab Created Rubies, emerald cut